I only knew about the signings in the last 15 years and managed to attend several of them - towards the end of his playing career, it would really be crazy getting to the car dealership early and staking out a spot in line.
As Gwynn retired, the appearances seemed to get a little more low key and manageable to attend - sometimes Gwynn would be grumpier than other times, but he would always to take the time to sign.
I'm not sure he did this all the time, but he'd usually extend the signing time an hour extra - a funny thing he always did do was bust the balls of 'collectors' who would line up a second time.
Gwynn was savvy as far as sniffing out the pros and at these signings and there maybe at least 20 of them that he regularly saw [plus everyone else who might have gotten back in line] - he'd make them wait in a separate line if he knew he'd sign for them already and make signing for fans who hadn't gotten an autograph a priority.
Maybe if he felt like he was done with everyone among the general public who made time to attend the signing - someone would need to give him a good reason before he relented to sign and finish up with the pros that stuck around.
A Hall of Famer who played much of his career in the 'junk wax era,' there was no doubt I first learned many of Gwynn's exploit through cardboard - I want to say he's a 'baseball card hero,' where I might not have actually seen many of his accomplishments as a player, but was aware of his reputation because of what was printed on the back of his baseball cards.